Method of removing caked material from pressure-filters.



No. 880,742. PATENTED MAR. s, 1908.

' D. J. KELLY. METHOD OF REMOVING GAKBD MATERIAL PROMTRESSURE FILTERS.

APPLICATION FILED JAN. 5. 1907.

auueutoz 13 i tn zooao UNITED STATES PATE T OFFICE.

DAVID J. KELLY, OF SALT LAKE CITY, UTAH, ASSIGNOR TO THE KELLY FILTER PRESS 00.,

I OF SALT LAKE CITY, UTAH, A CORPORATION OF UTAH.

METHOD OF REMOVING OAICED MATERIAL FROM PRESSURE-FILTERS.

Specification of Letters Patent.

Eatented March 3, 1908.

To all whom it may concern:

Be it known that I, DAvin J. KELLY, a citizen of the United States, residing at Salt Lake City, in the county of Salt Lake and State of Utah, have invented new and useful Improvements in Methods of Removing Caked Material from Pressure Filters, of which the following is a'specification.

My invention relates to a new and useful methodof loosening caked solid material from the sides of porous pressure filters, and my invention consists, essentially, in the 'admission of steam to the inside of a' hollow filter having porous walls, whereby the steam expands and penetrates the pores of the filter sides from the inside and attacks and softens the adhering inner side 'of the caked material and forms a film of moisture thereon which loosens the contact of the caked'material and allows said material to slick off so that it may bedischarged in substantially a compact form.

In the accompanying drawing I illustrate a simple form of apparatus capable of carrying out my process, but 'I do not limit my process to this or to any particular appa-f ratus except thatwhatever the form of apparatus used there must be present a hollow filter having porous walls and a steam supply which shall deliver steam into the space between the inner walls of the filter.

In said drawing, Figure 1, represents a part elevation and part sectional View of a pressure filter tank and a pressure filter diaphragm supported therein. Fig. 2, is a cross sectional view of the filter diaphragm.

My method is applicable to any art wherein it is desired to separate liquids from solid matter held in suspension and where the solid matter is collected in cake-like form uponthe outer sides of a ressure filter.

For instance, my method will be found of great value in the art of metallurgy in separating 'slimes from which precious metalshave been dissolved and the liquid which holds the precious metals in solution; it is also useful in the sugar industry.

The type of ap aratus herein shown as illustrative of one orm of apparatus which I may use for carrying out my method is substantially disclosed in an application filed by me on the 5th'day of January, 1907, Serial Number 350,971, and which apparatus comprises a pressure tank A, a pressure filter B therein and comprising canvas or other fabric D one, 0, being slotted longitudinally to receive the separated liquid and deliver the same outside the filter, and the other, D, being a steam pi e'leading from a mam E or other source 0 supply and delivering live steam directly into the hollow central space of the filter. The tank-may have a removable hopper-Joottom F which when opened allows the-loosened slime cake to be discharged from the tank by gravity in substantially a compact form.

In carrying out my process the material to be se arated is delivered'into the tank in any we 1 known manner under Whatever ressure may be desired, or found necessary.

he pressure of the solution in the tank forces the liquid constituents through the pores of the canvas or other sides of the filter to the inside from whence it is delivered by pipe 0; the solid constituents of the solution being too coarse. to pass through the pores of the canvas bank u on the outer sides thereof, and form a cal e of more or less hardened compact material. to a desirable thickness, the supply of solution is cut-off and the excess llquid having been drained from the pressure tank and .the

When this cake buildsbottom of same is removed, I now admit a fills the space-between'the inner surfaces of the porous filter sides and passes through the pores m-a direction 0 posite to that in which the solution passed t rough said sides, consequently the steam first attacks the inner surface of the "caked material and softens or dissolves the same until it' forms a thin film of moisture thereon with the result that the bond between the caked material and the pores of the filter sides is ru tured and the said material is permitted to slick 01f As this operation occurs before the caked material will become saturated with moisture from the steam, it is manifest that said material is thus permitted to be discharged by gravity and in a more or less compact form through the open bottom of the tank, and

without the assistance of mechanical or other the cake from the tank in substantially comtherefore it is not limited to the latter.

scraping devices. The steam also cleanses and opens the ores of the filter sides for a succeeding cyc e of operation.

I am aware that an exp ansible dry fluid, as compressed air, and also water under pres- 1 sure have been em loyed for loosening cakedmaterial from the porous sides of hollow filters and accordingly I do not claim the use of such substances as my invention. When compressed air is used, the expansive force of the same acts upon the caked-material so as to practically disintegrate it by forcibly ripping it from the sides of the filter; when water is used, the cake becomes su ersaturated and again disintegrated. ut when using steam and loosening the hardened cake by sim ly'creating a film of slime upon the inner ad ering sides, I do not materially disturb the internal and outer structure of the cake therefore I am enabled to deliver pact form.

My process is, of course,'equally a plicable to suction filters as well as pressure ters and In a suction filter, the .pi e conforming to the discharge'pipe for tered solution in the pressure filter is connected to a suction P5P? and the filter diaphragm being submerge 1n slime pulp, or like material to be filtered, in an. open tank, an external or atmospheric pressure is created in place'of direct pressure y means of a pressure tank. The caked material can be removed from the suction type of filter in the same'manner as from the pressure type.

Having t ius described my invention, what I claim as new and desire to secure by Letters Patent is The process herein describedof removing solid material adhering to the outer porous sides of a hollow filter, which process consists in admitting a volume of steam to the interior of the filter between said sides so that it will expand therein and outwardlyfipenetrate the pores of the filter and form a m of moisture on the inner surface of the solid material, and thereby allow said solid material to detach itself, in compact form, from the filter sides.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

DAVID J KELLY.

Witnesses:

ALBERT L. O. GENTER, ERNEST GAYFORD. 

